forcing guile to collect *all* garbage?

[Jon Trowbridge <trow@emccta.com>]

Is there anything that I can do to trigger an "aggressive" garbage
collection in guile, in which the whole heap would be scanned and I
could be sure afterwards that every lingering unreferenced object had
been deallocated?

I don't mind if this is a relatively slow operation --- lingering
unreferenced smobs are making it impossible for me to
deterministically flush some caches in the C++ back-end that I'm using
guile to scriptify...

Thanks,
-JT